Single axle roll control system that includes a dual chamber ball-screw mechanism

Abstract

A single axle suspension system including right and left dampers, first and second hydraulic circuits, and a first pressurizing mechanism connected in fluid communication with the first and second hydraulic circuits. The first pressurizing mechanism includes a dual chamber ball/screw mechanism to adjust the volumetric capacity of a pair of first and second variable volume chambers that are arranged in fluid communication with the first and second hydraulic circuits. Thus, the first pressurizing mechanism provides roll control by generating a pressure differential between the first and second hydraulic circuits, which causes an increase in the fluid pressure inside either the first working chamber of the right damper and the second working chamber of the left damper or inside the first working chamber of the left damper and the second working chambers of the right damper to provide roll stiffness that counters vehicle roll during cornering.

What is claimed is: 
     
       1. A single axle suspension system, comprising:
 right and left dampers each including a damper housing, a piston rod, and a piston that is mounted on the piston rod and arranged in sliding engagement inside the damper housing such that the piston divides the damper housing into first and second working chambers; 
 a first hydraulic circuit connecting the first working chamber of the right damper and the second working chamber of the left damper; 
 a second hydraulic circuit connecting the second working chamber of the right damper and the first working chamber of the left damper; and 
 a first pressurizing mechanism including a first variable volume chamber that is arranged in fluid communication with the first hydraulic circuit, a second variable volume chamber that is arranged in fluid communication with the second hydraulic circuit, and a ball/screw mechanism that is arranged to increase and decrease a volumetric capacity of each of the first and second variable volume chambers and generate a pressure differential between the first and second hydraulic circuits independent of damper movements to adjust a roll resistance of the single axle suspension system. 
 
     
     
       2. The single axle suspension system set forth in  claim 1 , wherein the first and second variable volume chambers of the first pressurizing mechanism are separated by a pair of driven pistons that are moveably driven by the ball/screw mechanism in a first direction to increase the volumetric capacity of the second variable volume chamber while decreasing the volumetric capacity of the first variable volume chamber and a second direction to decrease the volumetric capacity of the second variable volume chamber while increasing the volumetric capacity of the first variable volume chamber. 
     
     
       3. The single axle suspension system set forth in  claim 2 , wherein movement of the pair of driven pistons in the first direction causes hydraulic fluid to flow out of the first variable volume chamber and into the first hydraulic circuit to increase static pressure in the first hydraulic circuit, wherein movement of the pair of driven pistons in the first direction also causes hydraulic fluid to flow into the second variable volume chamber from the second hydraulic circuits to decrease static pressure in the second hydraulic circuit, wherein movement of the pair of driven pistons in the second direction causes hydraulic fluid to flow into the first variable volume chamber from the first hydraulic circuit to decrease static pressure in the first hydraulic circuit, and wherein movement of the pair of driven pistons in the second direction also causes hydraulic fluid to flow out of the second variable volume chamber and into the second hydraulic circuit to increase static pressure in the second hydraulic circuit. 
     
     
       4. The single axle suspension system set forth in  claim 3 , wherein the ball/screw mechanism of the first pressurizing mechanism includes a motor arranged to rotate a threaded rod to operably drive movement of the pair of driven pistons in the first and second directions such that the pair of driven pistons move in unison with one another. 
     
     
       5. The single axle suspension system set forth in  claim 4 , wherein the first hydraulic circuit includes a first hydraulic line extending between and connected in fluid communication with the first working chamber of the right damper and the second working chamber of the left damper and wherein the second hydraulic circuit includes a second hydraulic line extending between and connected in fluid communication with the second working chamber of the right damper and the first working chamber of the left damper. 
     
     
       6. The single axle suspension system set forth in  claim 5 , further comprising:
 a reservoir that is connected in fluid communication with a reservoir line; 
 a second pressurizing mechanism that is connected in fluid communication with the reservoir line and a third hydraulic line; 
 a first charge line extending between and connected in fluid communication with the first and third hydraulic lines; and 
 a second charge line extending between and connected in fluid communication with the second and third hydraulic lines. 
 
     
     
       7. The single axle suspension system set forth in  claim 6 , wherein the second pressurizing mechanism is a bi-directional pump. 
     
     
       8. The single axle suspension system set forth in  claim 7 , wherein the bi-directional pump of the second pressurizing mechanism has a first working mode where the bi-directional pump draws in hydraulic fluid from the reservoir line and discharges the hydraulic fluid into the third hydraulic line to increase static pressure in at least one of the first and second hydraulic circuits and wherein the bi-directional pump of the second pressurizing mechanism has a second working mode where the bi-directional pump draws in hydraulic fluid from the third hydraulic line and discharges the hydraulic fluid into the reservoir line to decrease static pressure in at least one of the first and second hydraulic circuits. 
     
     
       9. The single axle suspension system set forth in  claim 6 , further comprising:
 a first shut-off valve positioned along the first charge line; and 
 a second shut-off valve positioned along the second charge line, 
 wherein each of the first and second shut-off valves are electromechanical valves with an open position and a closed position and are configured to permit the second pressurizing device to increase or decrease static pressure in only the first hydraulic circuit, only the second hydraulic circuit, or both the first and second hydraulic circuits. 
 
     
     
       10. The single axle suspension system set forth in  claim 5 , further comprising:
 a first pressure control line extending between and connected in fluid communication with the first variable volume chamber of the first pressurizing mechanism and the first hydraulic line; and 
 a second pressure control line extending between and connected in fluid communication with the second variable volume chamber of the first pressurizing mechanism and the second hydraulic line. 
 
     
     
       11. The single axle suspension system set forth in  claim 5 , further comprising:
 a first bridge line extending between and interconnecting the first and second hydraulic lines at a location adjacent to the right damper; 
 a second bridge line extending between and interconnecting the first and second hydraulic lines at a location adjacent to the left damper; 
 a third shut-off valve positioned along the first bridge line; and 
 a fourth shut-off valve positioned along the second bridge line, 
 wherein each of the third and fourth shut-off valves are electromechanical valves with an open position and a closed position and are configured to provide a comfort operating mode in the open position where hydraulic fluid can flow freely between the first and second hydraulic circuits. 
 
     
     
       12. A single axle suspension system, comprising:
 right and left dampers each including a damper housing, a piston rod, and a piston that is mounted on the piston rod and arranged in sliding engagement inside the damper housing such that the piston divides the damper housing into first and second working chambers; 
 a first hydraulic line extending between and connecting the first working chamber of the right damper and the second working chamber of the left damper; 
 a second hydraulic line extending between and connecting the second working chamber of the right damper and the first working chamber of the left damper; and 
 a first pressurizing mechanism including a first variable volume chamber that is connected to the first hydraulic line via a first pressure control line, a second variable volume chamber that is connected to the second hydraulic line via a second pressure control line, and a ball/screw mechanism that is arranged to increase and decrease a volumetric capacity of each of the first and second variable volume chambers and generate a pressure differential between the first and second hydraulic circuits independent of damper movements to adjust a roll resistance of the single axle suspension system. 
 
     
     
       13. The single axle suspension system set forth in  claim 12 , wherein the first and second variable volume chambers of the first pressurizing mechanism are separated by a pair of driven pistons that are moveably driven by the ball/screw mechanism in a first direction to increase the volumetric capacity of the second variable volume chamber while decreasing the volumetric capacity of the first variable volume chamber and a second direction to decrease the volumetric capacity of the second variable volume chamber while increasing the volumetric capacity of the first variable volume chamber. 
     
     
       14. The single axle suspension system set forth in  claim 13 , wherein movement of the pair of driven pistons in the first direction causes hydraulic fluid to flow out of the first variable volume chamber and into the first pressure control line to increase static pressure in the first hydraulic line, wherein movement of the pair of driven pistons in the first direction also causes hydraulic fluid to flow into the second variable volume chamber from the second pressure control line to decrease static pressure in the second hydraulic line, wherein movement of the pair of driven pistons in the second direction causes hydraulic fluid to flow into the first variable volume chamber from the first pressure control line to decrease static pressure in the first hydraulic line, and wherein movement of the pair of driven pistons in the second direction also causes hydraulic fluid to flow out of the second variable volume chamber and into the second pressure control line to increase static pressure in the second hydraulic line. 
     
     
       15. The single axle suspension system set forth in  claim 14 , wherein the ball/screw mechanism of the first pressurizing mechanism includes a motor arranged to rotate a threaded rod to operably drive movement of the pair of driven pistons in the first and second directions such that the pair of driven pistons move in unison with one another. 
     
     
       16. The single axle suspension system set forth in  claim 12 , further comprising:
 a reservoir that is connected in fluid communication with a reservoir line; 
 a second pressurizing mechanism that is connected in fluid communication with the reservoir line and a third hydraulic line; 
 a first charge line extending between and connected in fluid communication with the first and third hydraulic lines; and 
 a second charge line extending between and connected in fluid communication with the second and third hydraulic lines. 
 
     
     
       17. The single axle suspension system set forth in  claim 16 , wherein the second pressurizing mechanism is a bi-directional pump that has a first working mode where the bi-directional pump draws in hydraulic fluid from the reservoir line and discharges the hydraulic fluid into the third hydraulic line to increase static pressure in at least one of the first and second hydraulic lines and a second working mode where the bi-directional pump draws in hydraulic fluid from the third hydraulic line and discharges the hydraulic fluid into the reservoir line to decrease static pressure in at least one of the first and second hydraulic lines. 
     
     
       18. The single axle suspension system set forth in  claim 16 , further comprising:
 a first shut-off valve positioned along the first charge line; and 
 a second shut-off valve positioned along the second charge line, 
 wherein each of the first and second shut-off valves are electromechanical valves with an open position and a closed position and are configured to permit the second pressurizing device to increase or decrease static pressure in only the first hydraulic circuit, only the second hydraulic circuit, or both the first and second hydraulic circuits. 
 
     
     
       19. The single axle suspension system set forth in  claim 12 , further comprising:
 a first bridge line extending between and interconnecting the first and second hydraulic lines at a location adjacent to the right damper; 
 a second bridge line extending between and interconnecting the first and second hydraulic lines at a location adjacent to the left damper; 
 a third shut-off valve positioned along the first bridge line; and 
 a fourth shut-off valve positioned along the second bridge line, 
 wherein each of the third and fourth shut-off valves are electromechanical valves with an open position and a closed position and are configured to provide a comfort operating mode in the open position where hydraulic fluid can flow freely between the first and second hydraulic circuits. 
 
     
     
       20. A single axle suspension system, comprising:
 right and left dampers each including a damper housing, a piston rod, and a piston that is mounted on the piston rod and arranged in sliding engagement inside the damper housing such that the piston divides the damper housing into first and second working chambers; 
 a first hydraulic circuit connecting the first working chamber of the right damper and the second working chamber of the left damper; 
 a second hydraulic circuit connecting the second working chamber of the right damper and the first working chamber of the left damper; 
 a first pressurizing mechanism including a first variable volume chamber that is arranged in fluid communication with the first hydraulic circuit, a second variable volume chamber that is arranged in fluid communication with the second hydraulic circuit, and a ball/screw mechanism that is arranged to increase and decrease a volumetric capacity of each of the first and second variable volume chambers and generate a pressure differential between the first and second hydraulic circuits independent of damper movements to adjust a roll resistance of the single axle suspension system; and 
 a second pressurizing mechanism including a bi-directional pump that is connected in fluid communication with a reservoir and the first and second hydraulic circuits to selectively increase or decrease static pressure in the first and second hydraulic circuits by adding or removing hydraulic fluid to and from the first and second hydraulic circuits.